1. Technical Field
The present invention relates to improvements on electro-optical devices such as electro-luminescence (EL) displays.
2. Related Art
EL displays employ a current-driven luminescent body (organic EL or inorganic EL). Large-screen displays including the current-driven luminescent bodies require a significantly large amount of drive currents since the amount of drive currents is proportional to the area of the display unit.
Therefore, for example, an invention disclosed in JP-A-2000-89691 has made a proposal to construct each pixel with a plurality of organic EL elements that are connected in series and to thereby reduce the amount of a drive current flowing through the pixel, so as to reduce power-loss at the organic EL elements and drive transistors.
However, typically the organic EL display element has a multi-layered structure including an anode layer, a luminescent layer and a cathode layer, and has a diode characteristic of emitting light in response only to a forward bias current. When connecting in series plural organic EL display elements arranged in a matrix on a substrate, it is needed to couple the anode of an organic EL element with the cathode of a neighboring organic EL element. However, the anode and the cathode of the neighboring organic EL elements are disposed at different layer levels over the substrate. Accordingly, there arises a need to provide a structure for coupling the anode and the cathode of the neighboring organic EL elements. The existence of this coupling structure in the pixel region including organic EL display elements decreases the luminescent area per one pixel, which leads to lowering of the so-called aperture ratio, which is the ratio of the luminescent area to the pixel area.